We are given:
\[
I = \int_0^1 \left( x + 2x + 3x^2 + 4x^3 \right) \, dx
\]
Simplifying the integrand:
\[
I = \int_0^1 (3x + 3x^2 + 4x^3) \, dx
\]
Now, integrate each term:
\[
I = \left[ \frac{3x^2}{2} + \frac{3x^3}{3} + \frac{4x^4}{4} \right]_0^1
\]
Evaluating the definite integral:
\[
I = \left[ \frac{3(1)^2}{2} + \frac{3(1)^3}{3} + \frac{4(1)^4}{4} \right] - \left[ 0 \right]
\]
\[
I = \frac{3}{2} + 1 + 1 = \frac{7}{2}
\]
Thus, the correct answer is \( \frac{7}{2} \).